• Authors:
    • Kaneko, N.
    • Komatsuzaki, M.
    • Yagioka, A.
    • Ueno, H.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 200
  • Year: 2015
  • Summary: Abandoned agricultural land could potentially accumulate soil organic carbon (SOC) when it is no longer used for cultivation and is allowed to revert to natural vegetation. In Japan, no tillage with weed mulching will be adopted in marginal farmland as a new organic farming system because this system minimizes the disturbance of the soil ecosystem and reduces the cost for crop production. The present study aimed to compare the effects of two organic farming systems, namely no-tillage with weed cover mulching and conventional tillage (CT), and two organic fertilizer application modes, namely no fertilizer (N-) and organic fertilizer (N+; 50kgNha-1 during 2010 and 2011 and 80kgNha-1 during 2012) on greenhouse gas (GHG) fluxes, soil carbon sequestration, net global warming potential (GWP), and nitrate leaching. Pumpkin (Cucurbita spp.) was cultivated as the main crop in 2010 and 2011, whereas mixed cropping of okra (Abelmoschus esculentus L.), bell pepper (Capsicum annuum L.), and eggplant (Solanum melongena L.) was implemented in 2012. Tillage management increased CH4 uptake immediately after the tillage; however, the effects did not continue in the long term. On the contrary, NTW increased CH4 uptake, and the soil carbon content at the soil surface linearly increased every year after conversion to NTW indicating that improving soil physics by continuing NTW contributed to enhanced CH4 uptake. N2O emissions in NTW were higher only immediately after a weed mowing; however, NTW did not increase the annual N2O emission. In addition, the difference between initial and final SOC (dSOC) was greater in NTW than in CT, which significantly decreased net GWP in NTW in comparison with CT. Nitrate leaching was 48.6% and 47.3% lower in NTW than in CT at soil depths of 30-60 and 60-90cm, respectively. These results show that no-tillage with weed cover mulching contributed to conserve the regional and global environment by reducing nitrate leaching and net GWP from the agro-ecosystem by increasing the annual CH4 uptake and soil carbon sequestration. This system will be adopted for abandoned agricultural land because it reduces net GWP shortly after conversion to this management.
  • Authors:
    • Suh, Sangwon
    • Yang, Yi
  • Source: INTERNATIONAL JOURNAL OF LIFE CYCLE ASSESSMENT
  • Volume: 20
  • Issue: 2
  • Year: 2015
  • Summary: Purpose Rising corn prices in the USA due partly to increasing ethanol demands have led to a significant expansion of corn areas displacing natural vegetation and crops including cotton. From 2005 to 2009, cotton area harvested in the USA nearly halved with a reduction of 2.5 million hectares, while that of corn increased by 1.8 million hectares. However, environmental impacts of land shifts from cotton and corn have been largely neglected in literature. Methods In this study, we evaluate the environmental properties of US corn and cotton production and implications of land cover change from cotton to corn using state-specific data and life cycle impact assessment. Focusing on regional environmental issues, we cover both on-farm direct emissions such as different types of volatile organic compounds and pesticides and indirect emissions embodied in input materials such as fertilizers. TRACI 2.0 is used to evaluate the environmental impacts of these emissions. Results and discussion The results show that US cotton and corn productions per hectare on average generate roughly similar impacts for most impact categories such as eutrophication and smog formation. For water use and freshwater ecotoxicity, corn shows a smaller impact. When land shifts from cotton to corn in cotton-growing states, however, the process may aggravate most of the regional environmental impacts while relieving freshwater ecotoxicity impact. The differences in the two estimates are due mainly to underlying regional disparities in crop suitability that affects input structure and environmental emissions. Conclusions Our results highlight the importance of potential, unintended environmental impacts that cannot be adequately captured when average data are employed. Understanding the actual mechanisms under which certain policy induces marginal changes at a regional and local level is crucial for evaluating its net impact. Further, our study calls for an attention to biofuel-induced land cover change between crops and associated regional environmental impacts.
  • Authors:
    • Lv, Y. Z.
    • Huang, F.
    • Zhao, N.
    • Yang, Z. C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. A
  • Year: 2015
  • Summary: The aim of the study is to analyze the effects of different fertilization of organic and inorganic fertilizers on soil organic carbon (SOC) sequestration and crop yields after a 22 years long-term field experiment. The crop yields and SOC were investigated from 1981 to 2003 in Dry-Land Farming Research Institute of Hebei Academy of Agricultural and Forestry Sciences, Hebei Province, China. The dominant cropping systems are winter wheat-summer corn rotation. There were totally sixteen treatments applied to both wheat and corn seasons: inorganic fertilizers as main plots and corn stalks as subplots and the main plots and subplots all have four levels. The results revealed: after 22 years, mixed application of inorganic fertilizers and crop residuals, the SOC and crop yields substantially increased. Higher fertilizer application rates resulted in greater crop yields improvement. In 2002-2003, wheat and corn for the highest fertilizer inputs had the highest yield level, 6400kgha-1 and 8600kgha-1, respectively. However, the SOC decreased as the excessive inorganic fertilizer input and increased with the rising application of corn stalks. The treatment of the second-highest inorganic fertilizer and the highest corn stalks had the highest SOC concentration (8.64gCkg-1). Pearson correlation analysis shows that corn and winter wheat yields and the mineralization amount of SOC have significant correlation with SOC at p<0.05 level.
  • Authors:
    • Yu, H.
    • Bolan, N.
    • Luo, J.
    • Ding, W.
    • Zhang, H.
  • Source: Soil and Tillage Research
  • Volume: 148
  • Year: 2015
  • Summary: Soil aggregates play a central role in the soil organic carbon (SOC) sequestration. To understand the stabilization process of exogenous easily decomposable organic C in soil and aggregates, 13C-glucose was supplied to arable soils following a 20-year application of compost (CM), inorganic NPK (NPK) and a control (no fertilizer, CK). Soil was fractionated into large macroaggregate (>2000µm), small macroaggregate (250-2000µm), microaggregate (53-250µm), silt fraction (2-53µm) and clay fraction (CNPK>CCK over the entire incubation. The content of glucose-derived 13C in large and small macroaggregates decreased gradually, but steadily increased in the silt and clay fractions in all treatments over the 30-day incubation period. However, glucose-derived 13C in microaggregates remained at the constant level during the incubation. Our findings indicate that the proportion of 13C protected from dissolving in water during wet-sieving increased with the incubation, and the exogenous easily decomposable organic C could be more effectively maintained in organic C-rich soil (CM) than in organic C-poor soil (CK or NPK). Clearly, glucose-derived 13C was sequestrated and stabilized gradually in soil by redistribution from macroaggregates to silt and clay fractions.
  • Authors:
    • Medina, E.
    • Aragüés, R.
    • Zribi. W.
    • Faci, J. M.
  • Source: Soil and Tillage Research
  • Volume: 148
  • Year: 2015
  • Summary: Soil evaporation is an important component of the water balance in irrigated agriculture. Mulching can be an effective technique to reduce soil evaporation but its efficiency depends on meteorological conditions and the characteristics of the different mulching materials. The objective of this work was to assess the effectiveness of inorganic (plastic) and organic (pine bark, vine pruning residues, geotextile, and wheat straw) mulching materials for soil evaporation control during the energy-limited and falling-rate evaporation stages. Soil evaporation rates (ER) were quantified through consecutive weighings of initially wet soils placed in trays in the laboratory and in microlysimeters in the field. ER depended on meteorological and experimental conditions, stage of evaporation and type of mulching material. In the falling-rate stage, ERs decreased linearly ( p<. 0.001) with decreases in GWC, and for long drying periods the ERs were low and similar among treatments, implying that soil mulching will be ineffective for soil evaporation control in low-frequency irrigation systems. In the energy-limited stage, all mulching materials decreased the ERs in relation to the bare soil, but the plastic, vine residues and pine bark materials had lower ERs than the rest of mulching materials. These materials will be therefore recommended for soil evaporation control in high-frequency irrigation systems where the soil surface remains wet most of the time.
  • Authors:
    • Pearn, K.
    • Balek, J.
    • Sandars, D.
    • Sanchez, A.
    • Maspons, J.
    • Sabate, S.
    • Trnka, M.
    • Audsley, E.
  • Source: CLIMATIC CHANGE
  • Volume: 128
  • Issue: 3-4
  • Year: 2015
  • Summary: Studies of climate change impacts on agricultural land use generally consider sets of climates combined with fixed socio-economic scenarios, making it impossible to compare the impact of specific factors within these scenario sets. Analysis of the impact of specific scenario factors is extremely difficult due to prohibitively long run-times of the complex models. This study produces and combines metamodels of crop and forest yields and farm profit, derived from previously developed very complex models, to enable prediction of European land use under any set of climate and socio-economic data. Land use is predicted based on the profitability of the alternatives on every soil within every 10' grid across the EU. A clustering procedure reduces 23,871 grids with 20+ soils per grid to 6,714 clusters of common soil and climate. Combined these reduce runtime 100 thousand-fold. Profit thresholds define land as intensive agriculture (arable or grassland), extensive agriculture or managed forest, or finally unmanaged forest or abandoned land. The demand for food as a function of population, imports, food preferences and bioenergy, is a production constraint, as is irrigation water available. An iteration adjusts prices to meet these constraints. A range of measures are derived at 10' grid-level such as diversity as well as overall EU production. There are many ways to utilise this ability to do rapid What-If analysis of both impact and adaptations. The paper illustrates using two of the 5 different GCMs (CSMK3, HADGEM with contrasting precipitation and temperature) and two of the 4 different socio-economic scenarios ("We are the world", "Should I stay or should I go" which have contrasting demands for land), exploring these using two of the 13 scenario parameters (crop breeding for yield and population) . In the first scenario, population can be increased by a large amount showing that food security is far from vulnerable. In the second scenario increasing crop yield shows that it improves the food security problem.
  • Authors:
    • Ippolito, J. A.
    • Barbarick, K. A.
    • McDaniel, J.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 1
  • Year: 2015
  • Summary: The USEPA adapted a risk assessment approach in biosolids regulations that includes the use of an uptake coefficient (UC) (i.e., the ratio of plant concentration to quantity of element added) to determine limitations on selected elemental additions. The nature of the risk assessment requires UCs to be constants. Our hypothesis was that the UC for Cu, Fe, Mo, Ni, P, and Zn for biosolids-amended dryland winter wheat ( Triticum aestivum L.) decreases with multiple biosolids applications at the same location. We applied up to 10 applications to two sites (designated North Bennett A and B) in eastern Colorado at rates from 2.24 to 11.2 Mg ha -1 per application from 1993 to 2013. Results indicated that grain concentrations for all six elements followed no discernible trend as the number of biosolids applications increased. The UC values for these elements compared with the number of biosolids applications followed exponential decay models ( R2 ranged from 0.329 to 0.879). Consequently, UC values will likely not provide constants for risk assessment where multiple biosolids applications are made on the same site. We found that the slope between cumulative elemental removal by grain (kg ha -1) to the cumulative amount of element added with biosolids (kg ha -1) provides a constant over the number of biosolids additions ( R2 ranged from 0.471 to 0.990). As compared with the USEPA approach, our strategy of looking at cumulative changes may provide better estimations of wheat-grain concentrations for risk assessment of biosolids-borne elements.
  • Authors:
    • Skourtos, M.
    • Simpson, G.
    • Rowlands, O.
    • Kontogianni, A.
    • Chen, M. P.
    • Brown, S.
    • Berry, P. M.
  • Source: CLIMATIC CHANGE
  • Volume: 128
  • Issue: 3-4
  • Year: 2015
  • Summary: Adaptation and mitigation are complementary strategies for addressing the impacts of climate change, yet are often considered separately. This paper examines the literature for evidence of the interactions of adaptation and mitigation measures across the agriculture, biodiversity, coasts, forests, urban and water sectors, focusing on Europe. It found that often adaptation and mitigation synergies and conflicts were not explicitly mentioned within a sector, let alone between sectors. Most measures, however, were found to have an effect on another sector, resulting in neutral, positive (synergies) or negative (conflicts) interactions within and between sectors. Many positive cross-sectoral interactions involved biodiversity or water and thus these could represent good starting places for the implementation of integrated, cross-sectoral strategies. Previous studies suggest that adaptation and mitigation are undertaken on different time and geographical scales; this study found many local scale measures which could facilitate integration between both adaptation and mitigation. It is important that cross-sectoral interaction of adaptation and mitigation measures are explicitly recognised if they are to be mainstreamed into policy, so that positive outcomes are enhanced and unintended consequences avoided.
  • Authors:
    • Bouma, J.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 79
  • Issue: 2
  • Year: 2015
  • Summary: The introduction of information and communication technology (ICT) has fundamentally changed the flow and role of data and information in our increasingly digital society and this also strongly affects soil science. Stakeholders become more knowledgeable and critical. This issue paper raises the question as to how the scientific community, and particularly soil science, can best deal with the implications of the ICT revolution. Problems are evident when studying sustainable development, presenting "wicked" environmental problems that defy simple, straightforward solutions because many stakeholders are involved with contrasting opinions and interests, only allowing development of alternative options. A suggestion is made to establish Communities of Scientific Practice that interact with societal partners and the policy arena in a long-duration joint learning mode, promote and safeguard science quality and offer broad career perspectives for soil scientists. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved.
  • Authors:
    • Rounsevell, M.
    • Savin, C.
    • Cojocaru, G.
    • Murray-Rust, D.
    • Brown, E.
    • Brown, C.
  • Source: CLIMATIC CHANGE
  • Volume: 128
  • Issue: 3-4
  • Year: 2015
  • Summary: Many models have been developed to explore the likely consequences of climate change. These models tend to focus on single physical or socio-economic sectors and their processes, and neglect the many feedbacks that occur between the different components of the real world. To overcome this problem, models are increasingly being combined in integrated assessment platforms (IAPs), of which the CLIMSAVE IAP is an example, modelling cross-sectoral impacts, adaptation and vulnerability to climate change in Europe by combining 10 different meta-models that focus on specific sectors. Where models are combined in this way, however, attention must be given to the potential errors and uncertainties that integration might introduce. We present a quantitative uncertainty analysis of selected outputs of the CLIMSAVE IAP based on creating and sampling from probability density functions (PDFs) of each of the IAP's input variables to take account of model and scenario uncertainty. We find limited uncertainties in aggregate outputs of the IAP, which allow specific impacts to be predicted with definable levels of confidence. However, we also find substantial overlap between different socio-economic scenarios at the European scale, suggesting that changes to socio-economic conditions cannot reliably overcome climate-related uncertainty. Nevertheless, there is evidence that particular adaptation actions may significantly alter the impacts of climate change, especially at local or national scales.